Transformer for electric-arc cutting and welding apparatus



July 25, 1927. 7, 37

F. C. OWEN TRANSFORMER FOR ELECTRIC ARC CUTTING AND WELDING APPARATUSFiled April 15,- 1926 6 H w Y Patented July 26, 1927.

* UNITED STATE' S 1,631,237 PATENTQOFF'ICE.

j I FREDERICK CARLISLE OWEN, 0F FAYETTEVILLE, NORTH'GAROLINA.

TRANSFORMER FOR ELECTRIC-ARC CUTTING AND WELDING A PBARATUS.

Application filed Apri1 15, 1926, Serial No. 102,235.

, This invention relates to alternating current electric are cutting andwelding apparatus, and more particularly to a novel transformertherefor.

The invent-ion has for one of its objects the provision of a transformerwhich shall be admitted to permit an are which is uniform and will notburn the work to be easily maintained and which will efiicientlyfunction without the aid of damping devices, rheostats, resistances andthe like.

" A further and important object of the invention is the provision of atransformer of the character stated wherein the induced voltage per turnof the secondary winding 1 shall be greater than the impressed voltage fI per turn of the primary winding, whereby -=toreduce to the minimum thecurrent re ,-quired for the efiicient welding of any metal with either acoated, covered or bare electrode.

WVith the foregoing and other objects in view, the nature of which willappear as the description proceeds, the invention consists of thecombination and arrangement of parts hereinafter fully described andclaimed, and illustrated in the accompanying drawing, wherein: p

Figure 1 is a diagrammatic view of an arc weld ng apparatus embodyingthe transformer, and

' Figures 2, 3 and 4 are similar views of,

slightly modified forms of the transformer. Corresponding and like partsare referred to in the following description, and designated in theseveral views of the accompanying drawing, by similar reference characters. The transformer comprises a laminated core 1 which is preferablythough not necessarily of rectangular formation. The core 1. providesbut a single metallic magnetic path, and in practice is preferablysupported in a vertical position.

The primary circuit or winding of the transformer comprises connectedcoils 2, 3, 4 and 5 arranged on three adjacent legs of the core 1. Thecoils 2 and 3 are preferably mounted on the bottom leg and the coils 4and 5 on the side legs of the core 1. The coils 2 and 3 are reverselyarranged. Leads 6 and 7 extending from any suitable source of currentsupply 'ajre connected to the terminals of the primary winding.

The secondary circuit of the transformer comprises a main or voltageregulating coil 8 mounted on the bottom leg of the core 1,

and an auxiliary or current regulating coil 9 mounted on thetop leg ofthe core 1. The. coils 8 and 9 are reversely wound or reverselyconnected, so that thevoltages are added when connected in series by awire 10. The coil 9 has a greater number of turns or convolutions thanthe coil 8, and extending from certain turns or convolutions thereof aretap leads 11, any one of which may be connected to the electrode 12 by alead 13. Thecoil 8 is to be connected to the work 14 by a lead 15.

Current flowing through the primary winding causes a magnetic flux tocirculate through the four legs of the core 1. The back voltage in thiswinding is held down to the minimum due to the fact that this windingembodies a reversely arranged coil.

The back voltage in the reversely arranged coil is in opposition to thecorresponding voltage in the remainder. of the coil, and causes aleakage of the flux for the bottom leg of the coral at the ends of thiscoil. This flux leakage is particularly noticeable at the lower lefthandcorner of the core 1. This results in the lowering of the efiective backvoltage in the primary winding and a consequent higher exciting currentand greater flux density in .the core. In other words, the effect of thereversed coil of the primary winding is a greater induced voltage perturn in the secondary winding than the impressed voltage per turn in theprimary winding. It, will thus be apparent that the efficient welding ofany metal with either a coated, covered or bare electrode is'possiblewith the use of but a comparatively small amount of current.

Practically all the flux developed by the primary winding -will threadthe main or voltage regulating coil 8, because of the close associationof this secondary coil with the primary, and flux in this part of thegenerated by the primary winding. Owing to the location of the coils,this secondary flux is confined substantially to the to leg of thecore 1. The primary flux threa s the bottom and side legs of'the core,and also tends to permeate the top leg. In' this top leg, however, it isopposed and choked back by the flux due to the' secondary Winding 9, andas the result there will be a certain amount of flux leakage from eachend of the .primary coils 4 and 5. Owing to tl1eoppos ing and chokingeffect of the secondary coil 9, however, a very exaggerated leakagetakes place at the two upper corners ofthe core. or,- in other words,far the greatest pro: portion offiux i-sforced out of the closednetallicpath into the air at these points,

The larger the current drawn from the secondary winding, the greaterthis leakage becomes.

As the' result of such leakage, the heavy secondary flux causes the coil9 to develop high inductance, and act as an impedance coil, so that thephase of the voltage in this art of the secondary winding is shifted. heresulting voltage at the-arc is'therefore reduced, or at least preventedfrom increasing as the'current increases. The impedanceaction increaseswith the load, so-

that even on short circuit serves to prevent an excessive or dangerousflow of current. Thus a stable arc is maintained.

, In the modified form of the invention shownin Figure 2, the coils" 2and t are reversely arran ed as are also the coils 3 and 5, and a thirdlead 16,extending from a soiirce of current supply, is connected to theremote terminals of the coils 2 and 3. In this form of. the invention,the entire primary winding, or only one-half thereof consisting ofeither the coils 2 and 4 or the coils 3 and 5 may be employed. In Figure3, the coils 2, 3, 4 and 5 are connected in parallel;.. that is thecoils 2 and 4 and the coils 3 and 5 are paralleled. This form of theinvention is especially adapted for heavy welding and cutting. In theform, of the invention shown in Figure 4, the primary winding consistsof but two coils 2" and 4.

reverselyarranged. It is to be understood that I am not to berestrictedto the'arrangement of the secondary coils on the top and bottom legs ofthe core, as suchcoils maybe as shouldbe apparent arranged on any two ofthe-legs."

What is claimed is:-- 1. A transformer having a rectangular coreproviding. but; a single metallic. magnetic path, a primary windingdistributed around three adjacent legsof the core and having 'are'versedpcoil, and a secondary comprising two sections, one secwindintion'being wound on'the middle one of said core providing but a singlemetalliemag-I netic path, a primary winding including a reversed coiland'distributed around three adjacent legs of the core, and a-secondarywinding comprising two coils mounted on different legs of the core.

3. A transformer comprising a. core providing but a single magneticpath, a primary winding embodying reversely arranged coils mounted onadjacent legs of the core, asecondary coil mounted on one of said legsof f the core,-and a second secondary coil mounted on another leg of thecore and connected to said first secondary coil.

4. A transformer comprising a core, a primary winding distributed aboutthe major portion of .the core and having a reversed coil, a secondarycoil on the minor I portion of the core, and a second secondar coilconnected to said first secondary c011 core.

5. A transformer -comprisin a core, a primary winding distributed a outa portion of the core and embodying reversely arranged coils, asecondary c'oil onrsaid por tion of the core, and a, second secondarycoil on another portion of the core and connected to said firstsecondary coil.

6. A transformer having a rectangular core, aprimary winding embodyingcoilson the bottom leg of the core and a 0011 on each side leg ofthe'core, the coils being connected, one of the coils on the bottom legand the coil on one of the side legs being reversely arranged and theother coil on the bottom leg and the coil on the other side leg beingreversely arranged, a secondary coil on one of said legs, and a secondsecondary coil on the fourth legof the core and connected to said firstsecondary coil.

7. A transformer havin a rectangular core, a primary winding emiodyingcoils on the bottom leg of the core and a'coil on each side leg' of thecore, the coils being connected, one of the coils on the bottom leg [andthe coil on one ofthe side legs being one, of said legs of the core, anda second secondary coil on the remaining leg of the core and connectedto said first secondary coil.

In testimony whereof I aflix my si ature. FREDERICK CARLISLE 0 EN..-

